Mutations at more than one locus may be involved in cystic fibrosis--evidence based on first-cousin data and direct counting of cases.

Cystic fibrosis was present in 35 of 5,265 first cousins of index cases with the disease. The gene frequency was estimated to be .0281 +/- .00544, using an improved method that allows for the influence of cousin sibship size upon the estimate. This figure is higher than that obtained by direct counting of cases in Victoria, Australia, from 1955-1979 (.0198… CONTINUE READING